Fluid device

ABSTRACT

A fluid device of the axial piston type having high and low pressure operating passages, one of which may be an inlet and the other an outlet depending upon the pumping or motoring function of the device. The fluid device which may be of the fixed or variable displacement type has a rotatable cylinder barrel with each end of a plurality of pistons disposed for reciprocation within cylinder bores in the cylinder barrel, and cylinder ports successively communicating each of the cylinder bores with arcuate inlet and outlet passages formed in a valving face disposed at one end of the cylinder barrel. The other ends of the pistons are drivingly engaged by an inclined thrust plate assembly disposed to impart a reciprocal stroking movement to the pistons within the cylinder bores as the cylinder barrel is rotated. In one example of the invention, the thrust plate assembly, the cylinder barrel and other rotating components of the fluid device are constructed of a sintered material enclosed in a plastic housing which is preloaded by a predetermined amount that is a function of the expansion forces exerted on the housing by the fluid pressure acting against the pistons within the cylinder bores. In a second example of the invention, a variable displacement fluid device is disclosed as having several means for varying the inclination of the thrust plate assembly with respect to the longitudinal axis of the shaft on which the rotating cylinder barrel is carried.

United States Patent 1 Bobier June 19, 19 73 [54] FLUID DEVICE [22]Filed: Aug. 3, 1970 [21] Appl. No.: 60,333

[56] References Cited UNITED STATES PATENTS 2,667,862 2/1954 Muller91/506 3,405,646 10/1968 91/488 2,298,850 10/1942 Vickers 91/4872,699,123 1/1955 Bonnette et a1. 91/505 2,975,720 3/1961 Schoellhammer91/499 3,009,422 11/1961 Davis 417/222 3,092,034 6/1963 Bartholomaus...91/499 3,256,782 6/1966 Ebert 92/122 3,384,028 5/1968 Thoma 91/5013,504,492 4/1970 Neukirch 60/53 A 2,704,232 3/1955 Johnston et al 308/1PM 2,709,339 5/1955 Edelmann et al.... 417/252 2,885,248 5/1959 White308/1 N 2,972,962 2/1961 Douglas 91/507 3,124,008 3/1964 Firth et a1.74/60 3,241,495 3/1966 Diedrich et al... 91/507 3,255,673 .6/1966 Thoma91/485 3,396,670 8/1968 Baits 91/506 3,457,873 7/1969 Fischer et a1.91/6.5 3,512,178 5/1970 Russell 4'17/218 FOREIGN PATENTS OR APPLICATIONS662,105 6/1949 Great Britain 415/219 7/1969 Germany ..91/506 l/l964Germany ..91/507 Primary Examiner-William L. Freeh Attorney-Andrew R.Basile [5 7] ABSTRACT A fluid device of the axial piston type havinghigh and low pressure operating passages, one of which may be an inletand they other an outlet depending upon the pumping or motoring functionof the device. The fluid device which may be of the fixed or variabledisplacement type has a rotatable cylinder barrel with each end of aplurality of pistons disposed for reciprocation within cylinder bores inthe cylinder barrel, and cylinder ports successively communicating eachof the cylinder bores with arcuate inlet and outlet passages formed in avalving face disposed at one end of the cylinder barrel. The other endsof the pistons are drivingly engaged by an inclined thrust plateassembly disposed to imparta reciprocal stroking movement to the pistonswithin the cylinder bores as the cylinder barrel is rotated. In oneexample of the invention, the thrust plate assembly, the cylinder barreland other rotating components of the fluid device are constructed of asintered material enclosed in a plastic housing which is preloaded by apredetermined amount that is a function of the expansion forces exertedon the housing by the fluid pressure acting against the pistons withinthe cylinder bores.

In a second example of the invention, a variable displacement'fluiddevice is disclosed as having several means for varying the inclinationof the thrust plate assembly with respect to the longitudinal axis ofthe shaft on which the rotating cylinder barrel is carried.

23 Claims, 11 Drawing Figures Patented June 19, 1973 3,739,691

4 Sheets-Shoot 1 INVENTOA? W/LF'RED 6'. 508/52 4 ShOlCl-Sht 2 PatentedJune 19, 1973 3,739,691

4 Shuts-Sh. I

FIG-6 IN vs/vrol? WILF'IEO 5. 608/ 77 Heron v1 FLUID DEVICE BACKGROUNDOF THE INVENTION 1. Field of the Invention The present invention relatesto fluid devices and particularly to those of the axial piston typewhich may function either as a fluid pump or as a fluid motor.

2. Description of the Prior Art Heretofore, fluid pumping or motoringdevices of the axial piston type have been constructed of a metallichousing having a revolving cylinder barrel with a plurality of parallelcylinder bores therein, within which pistons are reciprocated by meansof a thrust plate assembly or the like. A rotary valve mechanism in theform of cylinder ports at one end of the cylinder barrel alternatelyconnects each cylinder bore with an inlet and an outlet passage of thedevice as the cylinder bar rel is rotated.

The thrust plate assembly in fluid devices of the variable displacementtype normally takes the form of a yoke having transversely extendingpintles rotatably carried in bearings suitably mounted to the wall ofthe housing such that the entire force exerted against the thrust plateassembly due to the fluid pressure acting against the piston within thecylinder barrel bores is taken by the housing, thus necessitating astrong metal housing. Such metal housings are expensive in that theymust be cast molded and subsequently require a machining operation toprovide the necessary precision that is needed in such constructions. Itwould be desirable to provide a housing for such axial piston fluiddevices, constructed of a plastic material which would eliminate thesubsequent machining operations and the resulting expenses normallyincurred in using such metal housings. For example, housings constructedfor fluid devices having the same displacement capacity would costapproximately $2.00 for a metal housing as compared to $0.60 for ahousing constructed of a plastic material. The equipment needed tomanufacture a metal housing costs approximately $750,000.00 as comparedto $3,500.00 for an injection mold which would be used in constructing ahousing of a plastic material.

Further, heretofore fluid devices of the variable displacement typehave. used a thrust plate assembly which is normally of a metalconstruction such as cast iron or steel which, in addition to requiringsubstantial machining, adds to the overall weight of the device. Itwould be desirable to replace such cast iron and/or steel thrust plateassemblies with one constructed of a sintered material which,heretofore, has not been possible because of the high loads andcomplicated shape that such thrust plate assemblies require.

In addition to the high loads transmitted to the thrust plate assembly,suitable means must be provided which permit an easy movement of thethrust plate assembly with respect to the longitudinal axis of the driveshaft on whichthe cylinder barrel is rotated so as to vary the amount ofreciprocal stroking movement imparted to the pistons within the cylinderbores to thereby permit a selected variation in the displacement of suchaxial piston fluid devices.

In such previously constructed axial piston fluid devices,thedisplacement control mechanism used to control the inclination ofthe" thrust plate assembly with respect to the longitudinal axis of thedrive shaft has necessitated a different design for both the fixeddisplacement device and the variable displacement pump as thedisplacement control mechanism is normally constructed as part of thehousing in such variable displacement devices, thus requiring a largerhousing for the variable displacement device. Heretofore, if the samehousing were used for both variable and fixed displacement units, alarger housing would have been required since portions thereof would beused to mount the displacement control mechanism. The use of such avariable displacement housing in a fixed displacement unit results in anunduly large unit in proportion to its displacement. It would thereforebe desirable to provide a housing which is constructed for both variabledisplacement and fixed displacement devices without requiring a largerhousing for the variable displacement design.

It is also a conventional practice that such previously used deviceshave been normally constructed to use only one type of displacementvarying control mechanism, whereas it may be desirable to have a fluiddevice having a housing construction which is adaptable for use withmanual controls, pressure compensated controls and the like, thuseliminating the necessity of having several different housing designsfor the same capacity unit so as to accommodate different displacev mentcontrol applications.

Fluid devices of the axial piston type normally are characterized byhaving a valving face formed by a flat surface on which the cylinderbarrel normally runs in abutment and in a fluid sealing relationship.The abutting face of the cylinder barrel on which the cylinder ports aredisposed normally has been provided with arcuately spaced elevatedpressure pads disposed radially outwardly from the cylinder portsproviding a bearing surface on which the cylinder barrel rides in amanner which avoids excessive wear. Such bearing pads are more commonlyreferred to as Kingsbury Pads" and have functioned in an acceptablemanner in the past to compensate for wear and variations in oilviscosity due to changing temperatures and different fluids. In devicesof this type operating at high speeds and high pressures, considerabledifflculty may be experienced in providing a satisfactory runningsurface between the cylinder barrel and the valving face due to a lackof oil flow across the face of the cylinder barrel from the cylinderports to the Kingsbury pads.

It would therefore be desirable to provide a new and improved Kingsburypad for such axial piston fluid devices.

As speed and pressure is increased in such previously used fluiddevices, there is always an accompanying increase in noise. This generalincrease in noise with increased speed and pressure may be attributed toa number of factors in devices of the axial piston type. First, thesound frequencies generated by the device increase with speed as thecomponents of the device are subjected to increased alternating impactforces; second, the intensity of speed related sounds increases as theimpact forces between components of the device increase; and third, theexcitation spectrum of the significant piston harmonics also broadens,thus increasing the number of resonant responses.

It would therefore be desirable to provide a fluid device wherein theattendant noise and vibration levels are significantly reduced.

SUMMARY OF THE INVENTION The present invention, which will be describedsubsequently in greater detail, comprises a fluid pumping or motoringdevice of the axial piston type having construction which permits theadaptation of an outer plastic housing with a substantially largepercentage of the rotating parts thereof constructed of a sinteredmaterial, providing an axial piston fluid device adapted for use over awide range of applications.

It is therefore an object of the present invention to provide a rotaryfluid device of the axial piston type having an improved constructionwhich is readily adapted to low cost manufacturing.

It is also an object of the present invention to provide a rotary fluiddevice of the axial piston type having an improved cylinder barrelconstruction resulting in a reduction in surface wear and gallingbetween the cylinder barrel and the valving face.

It is also an object of the present invention to provide a rotary fluiddevice of the axial piston type having an improved thrust plate assemblyresulting in greater reliability and long life while operating at highpressures and temperatures, proportioned and simplified so that it canbe made inexpensively from sintered materials.

It is also an object of the present invention to provide a rotary fluiddevice of the axial piston type having a construction which contributesto the reduction in the general noise radiated by such a device.

It is also an object of the present invention to provide a rotary fluiddevice of the axial piston type having means for varying thedisplacement thereof, and a housing construction adaptable toaccommodate a variety of displacement varying mechanisms.

Other objects, advantages, and applications of the present inventionwill become apparent to those skilled in the art of such fluid deviceswhen the accompanying description is read in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS The description herein makes referenceto the accompanying drawings wherein like reference numerals refer tolike parts throughout the several views, and in which:

FIG. 1 is a longitudinal cross sectional view of a fluid deviceincorporating a feature of the present invention;

FIG. 2 is a longitudinal cross sectional view of the fluid deviceillustrated in FIG. 1 and taken generally on line 22 thereof;

FIG. 3 is a fragmentary transverse cross sectional view of the fluiddevice of FIG. 1 and illustrating a component thereof and takengenerally on line 3-3 of FIG.

FIG. 4 is a side view of the component illustrated in FIG. 3;

FIG. 5 is a fragmentary, exploded view of the fluid device illustratedin FIG. 1;

FIG. 6 is a fragmentary cross sectional view of a fluid deviceincorporating another feature of the present invention;

FIG. 7 is a transverse fragmentary cross sectional view of the fluiddevice illustrated in FIG. 6 taken on line 7-7 thereof; and

FIGS. 8-11 are fragmentary views of several modifications of the presentinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, andparticularly FIGS. 1 and 2, there is illustrated a fluid device in theform of an axial piston pump 10 comprising a housing 12 having a bodysection 14 constructed of a plastic material and a longitudinallydisposed bore 18 enclosed by a cap 20 secured to the body section 14 bybolts 22 extending axially through the cap 20 and the body section 14and threadedly engaging clamps 15. An O-ring 24 insures a fluid tightseal between the juncture of the body section 14 and the cap 20. Thebody section 14 includes a pilot portion 26 forming a mounting flange 28having mounting holes 30 extending therethrough to permit the mountingof the pump 10 at a desired location. The housing bore 18 provides achamber 32 in which a rotating group 33 is positioned. The rotatinggroup 33 includes a cylinder barrel 34 which is provided with aplurality of arcuately spaced cylinder bores 36, each having one end ofa piston 38 axially slidable therein. A plurality of cylinder ports 40axially aligned with each cylinder bore 36 communicate each of thecylinder bores 36 with a front face 42 of the cylinder barrel 34. Eachof the pistons 38 have spherical ends 44 on which are swaged socketedshoes 46. The cylinder barrel 34 is positioned axially between a valvingface 48 formed on the inner face of the cap 20 and an inclined thrustplate assembly 50. The valving face 48 serves in a well known manner toprovide a properly phased connection between the cylinder ports 40 and apair of arcuate ports 52 and 54 such that the cylinder ports 40communicate successively with the arcuate ports 52 and 54 as thecylinder barrel 34 rotates. The arcuate ports 52 and 54 are,respectively, connected to the external inlet and outlet connectionports 53 and 55 of the pump 10.

The piston shoes 46 have outwardly extending flanges 56 which arecontacted by an annular cage 58 with holes corresponding to each piston38. The annular cage 58 has a centrally disposed conical bore 62 adaptedto contact a spherical outer surface 64 of a collar 66 which is, inturn, carried on a drive shaft 68 that extends longitudinally throughthe housing bore 18. A spring 70 disposed between the piston end of thecylinder barrel 34 and the collar 66 exerts a force urging the face 42of the cylinder barrel 34 into engagement with the valving face 48,while at the same time biases the shoes 46 by means of the collar 66 andthe annular cage 58 into engagement with the thrust plate assembly 50.The drive shaft 68 is supported between bearings 72 and 74. The bearing72 is carried in a bore 75 of a decreased diameter at the thrust plateassembly end of the housing 12 while the bearing 74 (shown only inFIG. 1) is carried in a centrally disposed bore 76 within the cap 20.The drive shaft 68 is effective to transmit torque from a prime mover(not shown) to the cylinder barrel 34 through a splined drivingconnection 78 in a conventional manner. A conventional shaft seal 80 isprovided in the decreased diameter bore 75 and retained in position by asnap ring 82.

The cylinder barrel 34 is provided with a skirt portion 84 snugglyfitted in a recessed portion 86 at the piston end of the cylinder barrel34 to form an inner race 88 for roller bearings 90; the outer race 92 ofwhich is carried by the body section 14 in abutment with the thrustplate assembly in a manner which will be described in greater detailhereinafter. The skirted portion 84 has an annular inclined innersurface 96 extending upwardly from the cylinder barrel 34 andterminating in such a manner that the thrust plate assembly end 98 ofthe inner race 88 is flush with the thrust plate assembly end 100 of theroller bearings 90. Heretofore, fluid devices have been constructed withthe inner race of the hearing extending beyond the roller bearings thesame distance as the outer race. By having the end 98 of the inner race88 flush with the end 100 of the roller bearings 90, a greaterdiameter'of thrust plate assembly 50 with respect to the longitudinalaxis is provided which may increase the displacement capacity of thepump by as much as percent as compared to fluid devices heretoforeconstructed by allowing the pistons to operate on a larger piston borecircle. The piston bore circle is a circle defined by the longitudinalaxes of the pistons 38 as the same rotate about the longitudinal axis ofthe shaft 68. As the diameter of the piston bore circle is increased,the diameter of each piston bore 36 may likewise be increased, thus thedisplacement of the pump 10 may be increased without increasing theoverall size thereof.

The face 42 of the cylinder barrel 34 which is substantially identicalto the configuration illustrated in FIG. 7, comprises a plurality ofbearing pads 102, separated from one another by radial grooves 104 andseparated from the balancing lands 106 of the cylinder ports 40 by anannular groove 108. The bearing pads 102 are generally referred to asKingsbury pads and function in a manner well known in the art. Thebearing pads 102 are further provided with a concave contour on theinner wall 110 facing the cylinder ports 40 to provide a larger oil poolto aid in lubricating the bearing pads 102 as the cylinder barrel 34rotates. The oil pools decrease excessive wear during high temperatureand high speed operations, thereby increasing the life of the face 42 ofthe cylinder block 34.

As can best be seen in FIG. 7, the cylinder ports 40 are arranged in acircle, having a radius equal to the radius of the arcuate ports 52 and54 (shown in phantom lines in FIG. 7) so that communication will bemaintained throughout the full length of the arcuate ports 52 and 54.This communication will be interrupted whenever a cylinder port 40 movesacross a cut-off portion or space separating the arcuate ports 52 and54.

With reference to FIGS. 1 and 2, as the cylinder barrel 34 rotates, areciprocating stroking motion is imparted to the pistons 38 due to theinclination of the thrust plate assembly 50, thus a relativereciprocating motion between the cylinder barrel 34 and the pistons 38results as the cylinder barrel 34 rotates wherein the cylinder bores 36are alternately compressed and expanded, resulting in fluid being drawninto and expelled from the cylinder bores 36 through the cylinder ports40.

From the foregoing it can be seen that when a rotary movement isimparted to the outer end 112 of the drive shaft 68, the cylinder barrel34 will be revolved to alternately register the cylinder bores 36 withthe arcuate ports 52 and 54 of the valving face 48 by means of thecylinder ports 40.

Referring to FIGS. 1-5 for an understanding of the accompanyingdescription of the thrust plate assembly 56 which comprises a movableyoke 55 and a fixed yoke support 57. The fixed yoke support 57 has a U-shaped configuration, the bottom wall 59 of which has a bore 61 throughwhich the drive shaft 68 extends. The bore 61 has an end enlargedportion 63 having an inner diameter closely fitting the outer diameterof the drive shaft support bearing 72, and thus as can best be seen inFIG. 1 the yoke support 57 is axially aligned with respect to the driveshaft 68 when positioned on the outer periphery of the bearing 72.

The yoke support 57 includes a pair of axially projecting sidewalls 65,each of which has arcuately shaped bearing surface 67 supporting themovable yoke 55 on which the piston shoes 46 slidably engage as thecylinder barrel 34 is rotated so as to impart a reciprocal strokingmovement to the pistons 38. The yoke 55 has a pair of transverselyextending aligned support pins 69 and 71 each of which has arcuatelyshaped bearing surfaces 73 contoured to meet with the arcuately shapedbearing surfaces 67 of the projecting sidewalls 65 such that the yoke 55is adapted to pivot within the side wall bearing surfaces 67 about aaxis 75 defined by the radius of the transversely extending support pins69 and 71 in a manner which will be described in greater detailhereinafter.

The yoke support pin 71 includes a L-shaped arm 77 integrally formedtherewith and projecting rearwardly away from the support pin 71. Theprojecting leg of the arm 77 carries a member 79 (FIGS. 1 and 2) havinga slot 81 in which a connecting pin 83 is disposed. The connecting pin83 extends through an opening 85 formed in a sidewall of the bodysection 14 and is adapted to be coupled to any one of severaldisplacement varying mechanisms which will be described in greaterdetail hereinafter. As can best be seen in FIG. 8, the opening 85 is sosized as to permit the member 79 to be positioned therethrough onto thearm 77 during assembly with the connecting pin 63 extending through thehousing body section 14 and adapted to pivot about the axis 75 definedby the radius of the support pins 69 and 71 without interference withthe sidewall of the housing bore 85. As can best be seen in FIG. 2, thepreferred axis of rotation for the connecting pin 83 and for purposes ofdescription the longitudinal axis of the support pins 69 and 71, is theaxis 75 passing through the center point about which each of the arcuatebearing surfaces 73 is formed. The axis 75 should intersect the plane atwhich the centers of the spherical piston ends 44 lie and may alsointersect the longitudinal axis of the drive shaft 68. However, the axis75 may be vertically offset from the drive shaft axis, in a well knownmanner, depending upon the desired results.

The arcuately shaped bearing surfaces 67 formed on the sidewalls of theyoke support 57 are in the form of a plastic bearing 87, such asteflon-lead bearing or the like, which provides the necessary support towithstand the load transmitted through the pistons 38 and the movableyoke 55, while at the same time offering the least amount of frictionalresistance to the pivotal movement of the yoke 55 therewithin. Theplastic bearings 87 have a central aperture 89 (FIG. 5) adapted toreceive a boss 91 formed in each sidewall 65 to securely retain thebearing 87 on its associated sidewall 65.

The yoke 55 has a circular thrust bearing face 93 with which the shoes46 cooperate and a hemispherical cross section 95 (FIG. 5) with anelliptical, centrally disposed bore 97 through which the drive shaft 68extends. The elliptical shape of the bore 97 permits the yoke 55 torotate about the shaft 68 without interference therewith. Since the yoke55 and the yoke support 57 are both constructed of a sintered material,the radial thickness 99 (FIG. of support pins 69 and 71, as measuredfrom the bearing face 93 to the bottom of the support pin bearingsurface 73 must be at least 40 percent of the total thickness orlongitudinal length 101 of the yoke 55 as measured from the bearing face93 to the bottom thereof to assure that the yoke 55 will withstand theloads to which it is subjected, while the L-shaped arm 77 extending fromthe support pin 71 should have a length which is at least equal to theyoke thickness 101 in order to provide good fill characteristics whenthe same is manufactured.

The amount of friction between the bearing surfaces of the yoke 55 andthe yoke support 57 will be directly proportional to the load exertedthereon, while the frictional torque is in direct proportion to theradius of the arcuate bearing surfaces 67 or 73. In the present designthe radius of the bearing surfaces is kept to a minimum, and thus thefrictional torque minimized. It should also be noted that presentconstruction of the yoke 55 and the yoke support 57 results in thelength 103 and the thickness 101 of the yoke 55 being respectivelyshorter and greater than comparable components of presently useddevices. The shorter length and increased thickness of the yoke 55reduces unit vibrations and results in an extremely quiet pump comparedto such presently used designs.

Since the periphery of the yoke support 57 is rectangular and theperiphery of the yoke 55 is circular, each corner 117 of the yokesupport 57 will project radially outwardly beyond the yoke 55 asillustrated in FIG. 3 in phantom lines. As can best be seen in FIG. 2,the bearing 90 is axially positioned with respect to the center of eachpiston ball 44 by the abutment of the thrust plate facing side 94 ofouter race 92 against the corners 117 of the yoke support 57. Thisarrangement provides a simple construction which insures proper axialalignment, which is essential for a smooth, efficient andaccurateoperation of the pump 10.

Referring now to FIGS. 6 and 7 wherein there is illustrated amodification of the present invention in the form of a variabledisplacement axial piston pump 120 comprising a housing 122 having aninternal bore 124 enclosed by a cap 126 by means of screws (not shown)extending through the cap 126 and into threaded bores within the housing122, the pump 120 is similar to the pump disclosed in FIGS. 1 and 2 inthat it is provided with a drive shaft 68 on which a cylinder barrel 34is rotatably mounted and having a plurality of parallel cylinder bores36 and cylinder ports 40 through which fluid communication to arcuatepassageways 52 and 54 (FIG. 7) in the valving face 48 formed on theinner face of the cap 126 for directing fluid from an inlet port to anoutlet port. Radial support for the cylinder barrel 34 is provided byroller bearings 90 in the same manner as describe hereinbefore. Each ofthe cylinder bores 36 has a piston 38 reciprocably mounted therein withthe pistons 38, in turn, having rounded ends 44 on which piston shoes 46are positioned against a thrust plate assembly 50 by means of thecontact cage 58, the collar 66 and spring 70 in a manner substantiallyidentical as hereinbefore described.

The thrust plate assembly 50 comprises the fixed yoke support 57 carriedon the inner wall of the housing 122 by hearing 75 and includes a pairof axially projecting sidewalls 65, each of which has an arcuatelyshaped bearing surface 67 supporting a movable yoke 136 on which thepiston shoes 46 slidably engage as the cylinder barrel 34 is rotated soas to impart a reciprocal stroking movement to the pistons 38. The yoke136 has a pair of transversely extending, aligned support pins 138, eachhaving arcuately shaped bearing surfaces 140 contoured to mate with thearcuately shaped bearing surfaces 67 of the projecting sidewalls 65,such that the yoke 136 is adapted to pivot within the sidewall bearingsurfaces 67 about the axes 75 of the transversely extending support pins138 (only one of which is shown in FIG. 6). The yoke 136 includes a pairof transverse arms 142 and 144 which project in a plane perpendicular tothe support pins 138 and have rounded bearing surfaces 146 and 147 attheir projecting ends which respectively cooperate with a pair ofpistons 148 and 150 to rotate the yoke 136 within the bearing surface 67in a manner which will be described in greater detail hereinafter.

The pistons 148 and 150 are slidably mounted for reciprocal movement,respectively, within sleeve members 152 and 154 which, in turn, arecarried within stepped bores 156 in the cap 126. Each sleeve member 152and 154 has an enlarged end portion 158 which abuts a step 160 withinbores 156, and is secured to the cap 126 by screws 162 extending throughcover plates 164 and 166 into threaded bores 168 within the cap 126. Theinner ends of each sleeve member 152 and 154 abuts one side of the outerrace 92 of the roller bearings 90 to maintain the opposite side 94 ofthe outer race 92 in abutment with the corner 117 formed on the yokesupport 57 in the same manner hereinbefore described with respect to thepump 10. As can best be seen in FIGS. 6 and 7, the sleeve members 152and 154 have a sufficient radial thickness such that the pistons 148 and150 will traverse the outer surface of the outer race 92 withoutinterference therewith.

The sleeve member 152 has a spring 170 in compression between the coverplate 164 and the piston 148 biasing the piston 148 to engage the roundbearing surface 146 of the arm 142 and rotate the yoke 136 so as tostroke the yoke 136 to a full displacement position, that is, the yokeis at an angle with respect to the longitudinal axis of the drive shaft68 that permits the greatest degree of relative reciprocal strokingmovement between the pistons 38 and the cylinder bores 36.

The interior 153 of the sleeve member 154 is adapted to be communicatedto a source of pressure through a pressure compensated valve 172 or thelike, which selectively controls the pressure admitted to the interiorof the sleeve member 154 to move the piston 150 against the bearingsurface 147 of the arm 144 to selectively position the yoke forcontrolling the inclination of the thrust plate with respect to thelongitudinal axis of the drive shaft 68. Thus, the displacement of thepump 10 may be varied to provide any desired output from a minimumoutput to a maximum output.

The cylinder barrel 34, the piston shoes 46, the yoke 136 and the yokesupport 57 are all constructed of a sintered metal which, in addition toreducing the weight of the pump 120, increases the lubricatingcharacteristics of the rotating components and results in a fluid devicewhich is substantially less expensive to manufacture than fluid devicespreviously used.

Referring now to FIGS. 8-11 wherein there is illustrated severalmodifications of the present invention for varying the inclination ofthe thrust plate assembly 50 with respect to longitudinal axis of thedrive shaft 68 to control the displacement of the fluid pump 10. FIGS. 8and 9 there is illustrated a fragmentary cross sectional view ofmanually operated displacement control mechanism 180 with FIG. 8 being afragmentary crosssectional view taken on line 88 of FIG. 9. The controlmechanism 180 comprises an outer plastic housing 182 fastened to theplastic body section 14 by screws 184 extending therethrough intothreaded bores 185 in the plastic body section 14. The outer housing 182is carried by the body section 14 adjacent to the support pin 71 of themovable yoke 55. The manually operated displacement control mechanism180 includes a manually operated handle 196 rotatably mounted within abushing 198 extending through a bore 200 in the. outer housing 182. An()-ring 202 disposed in a recess 204 around the periphery of the handle196 provides a fluid 'tight seal preventing leakage from the interior ofthe fluid pump 10. The handle 196 is coupled to the connecting pin 83 bya pivot arm 194. When it is desired to vary this displacement of thepump 10, the handle 196 is manually rotated so as to pivot the pivot arm194, which, in turn, pivots the yoke 55 to any desired position.

FIG. 10 discloses a second displacement control mechanism 204 forvarying the displacement of the fluid pump 10 and comprises an outerplastic housing 206 having a cylindrical bore 208 in which a sleevemember 210 is slidably mounted. The outer housing 206 is mounted to theside of the plastic body section 14 adjacent the opening 85 and issecured to the pump 10 by a plurality of screws 209 extending throughthe outer housing 206 into the threaded bores 185 in the body section14.

One end of the sleeve member 210 has a threaded bore 212 in which athreaded stem 214 projecting from a knob 216 engages. The knob 216 isrotatably mounted in an aperture 217 extending through the housing 206and is secured in place by a retainer .ring 218 such that the knob 216may be rotated about the longitudinal axis of the, housing bore 208while being restrained against longitudinal movement by the retainerring 218. Thus, as the knob 216 is selectively rotated in .oppositedirections, the sleeve member 210 will be reciprocated within the boreof the housing under the driving action of the threaded stem 214. Theinner end of the sleeve member 210 has a bore 219 mounting theconnecting pin 83 which joins thesleeve member 210 to an arm 77 of thesupport pin 71 such that reciprocal movement of the sleeve member 210causes pivotable movement of the yoke 55, thereby permitting a selectedvariation in the displacement of the pump 10.

FIG. 1 1 illustrates a displacement control mechanism 224 of thepressure compensated type as having an outer plastic housing 226fastened to the plastic body section 14 adjacent the opening 85 byscrews 228 extending through the outer housing 226 into the threadedbores 185 in the plastic body section 14. The outer housing '226includes two parallel bores, one bore 230 having a pressure compensatorvalve232 carried therein, while the other bore 234 has a pressureresponsive piston member 236 slidably mounted therein which, in turn, isattached. to the yoke-55 by the connecting pin 83 extending through theopening 85 in the wall of the housing 12. Each of the bores 230 and 234are enclosed at their open ends by closure plates 244 and 245 secured tothe outer housing 226 by crews 246 or the like. The piston carrying bore234 has a spring 248 disposed between the closure plate 244 and the oneside of the pressure responsive piston 236 to bias the piston 236 towardthe other end of the bore 234. The pressure responsive piston 236 is soattached to the yoke 55 that the yoke 55 is normally pivoted toward amaximum flow position when piston 236 is positioned toward the closureplate 245 as illustrated in FIG. 10. The inner end 250 of the piston 236and the associated end of the bore 234 form a pressure chamber 252adapted to be selectively communicated to a source of fluid pressuregenerating a force acting on the piston 236 to move the piston 236against the bias of the spring 248 and stroke the yoke 55 toward aminimum displacement position. The pressure chamber 252 is supplied withfluid pressure through a passageway 254 in communication with the highpressure port of the device. The bore 234 is enlarged at the pressurechamber end to provide a path between the passageway 254 and thepressure chamber 252 which permits a construction having a minimumamount of passageways while at the same time allowing for a compactconstruction of the mechanism 224.

The pressure compensator valve 232 comprises a piston member 258 havingthe sealing land 260 adapted to control the amount of fluid through thepassageway 254 to the pressure chamber 252. The piston member 258 isnormally biased to a closed position by a spring 262 disposed betweenone end 264 of the piston member 258 and a second movable wall member266 which, in turn, is axially adjustable within the bore 230 by athreaded member 268 extending through the wall of the housing 226 andexternally thereof. By adjusting the position of wall member 266 withrespect to the piston end wall 264, the compression force of the spring262 may be varied to thereby vary the amount of force necessary to movethe piston 258. The piston end of the valve 232 is connected directly tohigh pressure passageway generating a force against the piston 258urging it against the bias of the spring 262. When the pressure of thepump 10 exceeds a predetermined value, the sealing land 260 is movedtoward an opened position permitting fluid pressure to pass thereby andinto the pressure chamber 252, generating the aforementioned force forurging the piston member 236 to move against the bias of the spring 248.A pressure between 200 psi and 300 psi acting against the piston member236 will move the same at sufficient distance to stroke the yoke 55 froma full flow or maximum displacement to a near zero flow or minimumdisplacement.

The plastic housing illustrated in FIG. 2 has an outer annular recessedportion 270 at the drive shaft end thereof on which the elongated metalclamps 15 are carried. By tighteningthe bolts 22 within threaded bore280 in the clamps 15, the plastic body section 14 may be precompressedto a predetermined amount, which is a function of the pressure at whichthe pump 10 will operate. During operation of the pump 10, the pressurewithin each cylinder bore 36 generates a force against each piston 38which acts in a direction normal to the face of the cylinder barrel 34.This force can be resolved in an axial component force and a radialcomponent force acting at the center of the spherical piston ends 44.These forces tend to exert a load on the plastic body section 14 of thehousing 12 which tends to longitudinally expand the same. Byprecompressing the plastic body section 14 by a predetermined amount,the effect of the expansion loads exerted on the plastic body section 14by internal forces of the rotating group 33 will be cancelled.

Thus, it can be seen that the present invention has provided a rugged,compact and low cost fluid device of the axial piston type that canfunction as a motor or a pump and which has an improved means formounting the cylinder barrel and for varying the displacement thereof.

While the forms of the embodiments of the invention as disclosedherewithin constitute a preferred form, it is to be understood thatother forms might be adopted, all coming within the spirit of theinvention and the scope of the appended claims.

What is claimed is as follows:

1. A fluid pressure energy translating device of the axial piston typecomprising:

a housing;

a cylinder barrel rotatably mounted about its longitudinal axis withinsaid housing, said cylinder barrel having a plurality of arcuatelyspaced cylinder bores communicating with both longitudinal ends of saidcylinder barrel;

a valve face having arcuate passages, said valve face and one end ofsaid cylinder barrel being disposed for relative rotary movement, withsaid cylinder barrel bores communicating successively with said arcuatepassages as said cylinder barrel rotates;

a plurality of pistons with inner ends disposed for reciprocal movementwithin said cylinder bores at the other end of said cylinder barrel;

a support member carried within said housing, said support member havinga pair of transversely spaced arcuately shaped bearing surfaces facingtoward said other end of said cylinder barrel;

a movable yoke constructed of a sintered metal material and having apiston engaging bearing surface on the side thereof facing the otherends of said pistons and cooperating therewith for imparting saidreciprocal movement to said pistons within said cylinder barrel bores assaid cylinder barrel rotates relative to said valve face, said movableyoke hav ing laterally extending integral support pins with arcuatelyshaped bearing surfaces pivotably supported in said support memberarcuately shaped bearing surfaces, each of said yoke support pins havinga radial thickness as measured from said piston engaging bearing surfaceto the periphery of the support pin arcuate bearing surface which isapproximately 40 percent of the longitudinal thickness of said movableyoke as measured from said piston engaging bearing surface;

means for varying the inclination of said piston engaging bearingsurface, said last mentioned means cooperating with said movable yoke topivot said movable yoke about an axis defined by said arcuately shapedbearing surfaces of said support pins, said means for varying theinclination of said piston engaging bearing surface comprising an armmember carried by and radially extending from one of said support pinsand pivotable therewith about the axes of said support pins, and adisplacement varying mechanism carried externally of said housing andoperatively coupled to said arm member to pivot said arm and saidmovable member about the longitudinal axes of said support pins, saiddisplacing varying mechanism comprising a second housing carried by saidfirst housing, said second housing having a longitudinal bore with asleeve member adapted to be selectively reciprocated therein, saidsleeve member having an internal threaded surface, a threaded memberrotatably mounted about an axis concentric with the longitudinal axis ofsaid second housing bore and restrained against movement along said lastmentioned longitudinal axis, said threaded member having a threadedportion engaging said sleeve threaded surface such that rotation of saidthreaded member in opposite directions causes relative reciprocalmovement between said sleeve member and said second housing bore, saidsleeve member being operatively coupled through an aperture in saidhousing arm member to pivot said arm member and said movable yoke aboutthe axes of said support pins.

2. A fluid pressure energy translating device of the axial piston typecomprising:

a housing having a longitudinal bore;

a cylinder barrel rotatably mounted about its longitudinal axis withinsaid housing bore, said cylinder barrel having a plurality of arcuatelyspaced cylinder bores communicating with both longitudinal ends of saidcylinder barrel;

a valve face having arcuate passages, said valve face and one end ofsaid cylinder barrel being disposed for relative rotary movement, withsaid cylinder barrel bores communicating successively with said arcuatepassages as said cylinder barrel rotates;

a plurality of pistons with inner ends disposed for reciprocal movementwithin said cylinder bores at the other end of said cylinder barrel;

thrust plate means having a piston engaging bearing surface on the sidethereof facing the other ends of said pistons and cooperating therewithfor imparting said reciprocal movement to said pistons within saidcylinder barrel bores as said cylinder barrel rotates relative to saidvalve face, said piston engaging bearing surface being constructed of asintered metal;

a shaft rotatably mounted in said housing along the longitudinal axis ofsaid bore, said cylinder barrel being drivingly connected to androtatable with said shaft;

bearing means carried at one end of said housing bore, said bearingmeans mounting said shaft for rotational movement, said thrust platemeans being mounted in said housing bore and having a portion thereof inabutment with said last-mentioned bearing means to provide both properradial alignment of said thrust plate means with said shaft and properalignment of said thrust plate means with said cylinder barrel when saidthrust plate means is mounted on said bearing means, and

wherein said one end of said cylinder barrel has a plurality of elevatedarcuately spaced bearing pads, said bearing pads being radiallyoutwardly spaced from said cylinder ports, the inner cylinder portfacing wall of each of said bearing pads having a concave contour.

3. A fluid pressure energy translating device of the axial piston typecomprising:

a housing having a longitudinal bore;

a cylinder barrel rotatably mounted about its longitudinal axis withinsaid housing bore, said cylinder barrel having a plurality of arcuatelyspaced cylinder bores communicating with both longitudinal ends of saidcylinder barrel;

a valve face having arcuate passages, said valve face and one end ofsaid cylinder barrel being disposed for relative rotary movement, withsaid cylinder barrel bores communicating successively with said arcuatepassages as said cylinder barrel rotates;

a plurality of pistons with inner ends disposed for reciprocal movementwithin said cylinder bores at the other end of said cylinder barrel;

thrust plate means having a piston engaging bearing surface on the sidethereof facing the other ends of said pistons and cooperating therewithfor imparting said reciprocal movement to said pistons within saidcylinder barrel bores as said cylinder barrel rotates relative to saidvalve face, said piston engaging bearing surface being constructed of asintered metal;

a shaft rotatably mounted in said housing along the longitudinal axis ofsaid bore, said cylinder barrel being drivingly connected to androtatable with said shaft;

bearing means carried at one end of said housing bore, said bearingmeans mounting said shaft for rotational movement, said thrust platemeans being mounted in said housing bore and having a portion thereof inabutment with said last-mentioned bearing means to provide both properradial alignment of said thrust plate means with said shaft and properalignment of said thrust plate means with said cylinder barrel when saidthrust plate means is mounted on said bearing means, said thrust platemeans comprises a support member carried in said housing bore and havinga portion thereof in abutment with said bearing means to provide aproper radial alignment of said support member with said shaft, saidsupport member having a pair of transversely spaced arcuately shapedbearing surfaces facing toward said other end of said cylinder barrel; amovable yoke constructed of a sintered metal material and having saidpiston engaging bearing surface formed on the said thereof facing saidother ends of said pistons, said movable yoke having latv erallyextending integral support pins with arcuately shaped bearing surfacespivotably supported in said support member arcuately shaped bearingsurfaces;

means for varying the inclination of said piston engaging surface;

bearing means having an outer race carried by said housing concentricwith said housing bore, said outer race having a portion of one sidesupported by each said support member;

an inner race carried around a portion of the peripheral surface of saidcylinder barrel;

a plurality of roller bearings disposed between said inner and outerraces; and

said means for varying the inclination of said movable yoke comprising apair of spaced sleeve members each disposed along axes paralleling theaxis of said shaft and radially spaced from the peripheral surface ofsaid cylinder barreL'eac'h of said sleeve members having one end of apiston member reciprocably mounted therein, the other ends of saidpiston members adapted to abut a portion of said movable yoke to pivotsaid movable yoke about the longitudinal axes of said support pins, saidsleeves being radially spaced a distance from the centerline of saidshaft axis to abut the outer race of said bearing means to maintain saidouter race in a supporting abutment with said support member, saidpiston members being carried within said sleeves and so spaced from saidlongitudinal axis of said shaft as to freely reciprocate in a spacedrelationship with respect to the outer periphery of said outer race.

4. The fluid pressure energy translating device defined in claim 3wherein the yoke facing ends of said roller bearings and said inner raceare substantially flush; a portion of said inner race extending beyondsaid other end of said cylinder barrel and having an annular inclinedinner surface flared upwardly from said other cylinder barrel end andtoward said yoke facing end of said inner race.

5. A fluid pressure energy translating device of the axial piston typecomprising:

a housing constructed of a plastic material;

a cylinder barrel rotatably mounted about its longitudinal axis withinsaid plastic housing, said cylinder barrel having a plurality ofarcuately spaced cylinder bores communicating with both longitudinalends of said cylinder barrel;

a valve face having arcuate passages, said valve face and one end ofsaid cylinder barrel being disposed for relative rotary movement, withsaid cylinder barrel bores communicating successively with said arcuatepassages as said cylinder barrel rotates;

a plurality of pistons with inner ends disposed for reciprocal movementwithin said cylinder bores atthe other end of said cylinder barrel;

a support member carried within said housing, said support member havinga pair of transversely spaced arcuately shaped bearing surfaces facingtoward said other end of said cylinder barrel;

a movable yoke constructed of a sintered metal material and having apiston engaging bearing surface on the side thereof facing the otherends of said pistons and cooperating therewith for imparting saidreciprocal movement to said pistons within said cylinder barrel bores assaid cylinder barrel rotates relative to said valve face, said movableyoke having laterally extending integral support pins with arcuatelyshaped bearing surfaces pivotably supported in said support memberarcuately shaped bearing surfaces, each of said yoke support pins havinga radial thickness as measured from said piston engaging bearing surfaceto the periphery of I the support pin arcuate bearing surface which isapproximately 40 percent of the longitudinal thickness of said movableyoke as measured from said piston engaging bearing surface;

means for varying the inclination of said piston engaging'bearingsurface, said last mentioned means cooperating with said movable yoke topivot said movable yoke about an axis defined by said arcuately shapedbearing surfaces of said support pins, said means for varying theinclination of said piston engaging bearing surface comprising an armmember carried by and radially extending from one of said support pins,and a displacement varying mechanism carried externally of said plastichousing and operatively coupled to said arm member to pivot said armmember about the axes of said support pins, said displacement varyingmechanism comprising a second housing carried by said plastic ciprocalmovement within said cylinder bores at the other end of said cylinderbarrel;

support member carried within said housing, said support member having apair of transversely spaced arcuately shaped bearing surfaces facingported in said support member arcuately shaped bearing surfaces, each ofsaid yoke support pins having a radial thickness as measured from saidpiston engaging bearing surface to the periphery of the support pinarcuate bearing surface which is approximately 40 percent of thelongitudinal thickness of said movable yoke as measured from said pistonengaging bearing surface; 4

means for varying the inclination of said piston engaging bearingsurface, said last mentioned means cooperating with said movable yoke topivot said movable yoke about an axis defined by said arcuately shapedbearing surfaces of said support pins, said housing having alongitudinal bore; a shaft rotatably mounted in said housing along thelongitudinal axis of said bore, said cylinder barrel being drivinglyconnected to and rotatable with said shaft, and bearing means carried atone end of said housing mounting said shaft for rotational movement,said support member being mounted in said housing bore and having aportion thereof in abutment with said last mentioned bearing means tohousing, said second housing having a longitudinal 5 provide properradial alignment of said support r h a sleeve m m r adapted to be r iprmember with said shaft, said movable yoke being cated therein, saidsleeve member having an interi d b id Support member h h id 1'13]threadfid Surface, a hreaded member rota y movable yoke is properlyaligned with said cylinder mounted a fixed Posmon 531d housmg and barrelwhen said yoke support is mounted on said adapted to rotate about alongitudinal axis of said bearing means Second housing bore, Saidthreaded member having 7. A fluid pressure energy translating device ofthe a portion thereof engaging said sleeve member axial piston typecomprising; such that rotation of said threaded member in opa housinghaving a longitudinal bore; Poslte directions Produces pl' moving Pacylinder barrel rotatably mounted about its longitutween Sleeve membersad secorfd housmg dinal axis within said housing, said cylinder barrelbore and Sleeve membef bmflg opefatwely' having a plurality of arcuatelyspaced cylinder k through an apertulje Plastic housmg to borescommunicating with both longitudinal ends said arm member to pivot saidarm member and of Said cylinder barrel; szfld movable yoke about theaxes of Said Support a valve face having arcuate passages, said valveface and one end of said cylinder barrel being disposed 6. A fluidpressure energy translating device the axial for relative rotarymovement with Said cylinder plston P sompnsmg: barrel borescommunicating successively with said l 1 b1 arcuate passages as saidcylinder barrel rotates; a mlder i f z mqmte 'g 8 a plurality of pistonswith inner ends disposed for reans ousmg Sal Cy m er ,arre ciprocalmovement within said cylinder bores at having a plurality of arcuatelyspaced cylinder the other end of said C H n dc r bane], borescommunicating with both longitudinal ends a pp member carrielii withinsaidhousing Sai d of said cylinder barrel;

support member having shaped bearing surfaces valve face having arcuatepassages, said valve face f acing toward said other end of said cylinderbarrel, and one end of said cylinder barrel being disposed bl k h b forrelative rotary movement with said cylinder amova eye 6 avmgaplstonengaging earmg Surface on the side thereof facing the other ends ofbarrel bores communicating successively with said arcuate p g as Saidcylinder barrel rotates. said pistons and cooperating therewith forimparta plurality of pistons with inner ends disposed for reg l i g g Ewllthm mi cy 1n er arre ores as sai cy 1n er arre rotates relative tosaid valve face, said movable yoke having complementary shaped bearingsurfaces cooperating with said support member shaped bearing surfaces;

toward Said other end of Said Cylinder barrel; means for varying theinclination of said piston ena movable yoke constructed of a sinteredmetal mategagmg f Surfajce last'memlonejd mearfs rial and having apiston engaging bearing Surface cooperating with said movable yoke topivot said on the side thereof facing the other ends of said pismovablek respect to Sam Support member tons and cooperating therewith forimparting said f bearing surfaces; a shaft rotfltablyfnoumd reciprocalmovement to said pistons within said 881d ousmg along the longitudinalaxis of said cylinder barrel bores as said cylinder barrel rotates boresald cylmder barfel bfimg g y 9 relative to said valve face, saidmovable yoke hav- "acted to f rotatable with i Shaft; i g ing laterallyextending integral support pins with earned at end of 531d housmgmounting arcuately Shaped bearing rf pivotably said shaft for rotationalmovement, said support member being mounted in said housing bore andhaving a portion thereof in abutment with said lastmentioned bearingmeans to provide proper radial alignment of said support member withsaid shaft, said movable yoke being carried by said support member suchthat said movable yoke is properly aligned with said cylinder barrelwhen said yoke support is mounted on said bearing means.

8. The fluid pressure energy translating device defined in claim 7wherein said housing is constructed of a plastic material.

9. The fluid pressure energy translating device defined-in claim 8wherein said plastic housing is longitudinally precompressed apredetermined amount which is a function of the force generated by thepressure of the fluid acting against the inner ends of said pistons,said force tending to longitudinally expand said plastic housing.

10. The fluid pressure energy translating device defined in claim 7wherein said shaped bearing surfaces on said support member areconstructed of a plastic material.

11. The fluid pressure energy translating device defined in claim 7,further comprising: a bearing means having an outer race carried by saidhousing concentrically with said housing bore, an inner race carriedaround the peripheral surface of said cylinder barrel, and a pluralityof roller bearings disposed between said inner and outer races, the yokefacing end of each of said roller bearings and said inner race beingsubstantially flush, a portion of said inner race extending beyond theother end of said cylinder barrel and having an annular inclined innersurface flared upwardly from said other cylinder barrel end toward saidyoke facing end of said inner race.

12. The fluid device defined in claim 7 wherein said support member isconstructed from a sintered metal material.

13. The device defined in claim 7 further comprising an arcuately shapedmember carried by said support member and defining said support membershaped bearing surface, said arcuately shaped bearing surfaces of saidmovable yoke support pins being received and supported by said bearingmembers, said bearing members being fabricated from a plastic material.

14. The device defined in claim 7 further comprising bearing meanshaving an outer race carried within said housing; an inner race carriedaround a portion of the peripheral surface of said cylinder barrel; anda plurality of roller bearings disposed between said inner and outerraces, said bearing means providing radial support for said cylinderbarrel as said cylinder barrel rotates, said bearing means beingproperly axially positioned within said housing by the abutment of oneside of one of said bearing races with a portion of said support member.

15. The fluid pressure energy translating device defined in claim 45,wherein said support member has a pair of transversely spaced arcuatelyshaped bearing surfaces facing toward said other end of said cylinderbarrel; a said movable yoke having said piston engaging bearing surfaceformed on the side thereof facing said other ends of said pistons, saidmovable yoke having laterally extending integral support pins with saidcom plementary shaped bearing surfaces being pivotably supported in saidsupport member arcuately shaped bearing surfaces; and means for varyingthe inclination of said piston engaging surface.

16. The fluid pressure energy translating devic'e defined in claim 15,wherein said means for varying the inclination of said piston engagingsurface cooperates with said movable yoke to pivot said movable yokeabout an axis defined by said arcuately shaped bearing surfaces of saidsupport pins.

17. The fluid pressure energy translating device in claim whereinsaid'means for varying the inclination of said movable yoke comprises:an arm member car ried at the end of one of said support pins andpivotable therewith about the axes of said support pins, and adisplacement varying mechanismcarried externally of said housing andoperatively coupled to said arm member to pivot said arm member and saidmovable yoke about the axes of said support pins.

18. The fluid pressure energy translating device defined in claim 17wherein said displacement varying said support pins as said manuallyoperated shaft is rotated in said second housing bore.

19. The fluid pressure energy translating device defined in claim 17wherein said displacement varying mechanism carried comprises: a secondhousing attached to said housing, said second housing having a bore witha pressure responsive member slidabiy mounted therein and biased to apredetermined position, valve means responsive to a predeterminedoperating pressure of said fluid device to supply a second pressure ofpredetermined value to said pressure responsive member to move saidpressure responsive member from said predetermined position, saidpressure responsive member being operatively coupled to said arm memberthrough an aperture in said device housing to pivot said arm member andsaid movable yoke about the axes of said support pins as said pressureresponsive piston moves from said predetermined position.

20. The fluid pressure energy translating device defined in claim 15,wherein said housing is constructed of a plastic material.

21. The fluid pressure energy translating device defined in claim 20wherein said means for varying the inclination of said movable yokecomprises: an arm member carried by and radially extending from one ofsaid support pins and pivotable therewith about the axes of said supportpins, and a displacement varying mechanism carried'externally of saidhousing and operably coupled to said arm member to pivot said arm memberabout said axes of said support pins, said displacement varyingmechanism comprising: a second housing-having a bore disposed along onaxis extending transversely of said shaft axis; a manually operatedshaft rotatably mounted in said second housing bore, a second arm memberradially extending from said second manually operated shaft andoperatively coupled through an aperture in said plastic housing to saidfirst mentioned arm member to pivot said first mentioned arm and saidmovable yoke about the axes of said support pins as said manuallyoperated shaft is rotated in said second housing bore.

22. The fluid pressure energy translating device defined in claim 20wherein said means for varying the inclination of said thrust platemovable yoke comprises: an arm member carried'by and radially extendingfrom one of said support pins and pivotable therewith along 23. Thefluid pressure energy translating device defined in claim 20 whereinsaid plastic housing is longitudinally precompressed a predeterminedamount which is a function of the longitudinal expansion forces exertedon said plastic housing by the pressure of the fluid acting against theinner ends of said pistons within said cylinder barrel bores,

I UNITED STATES PATENT OFFICE.

CERTIFICATE OF CORRECTION Patent; No. 3.739 91 I cL- Inventor(s) WilfredS. Bobier V It is certified tha t error appears in the above-identifiedpatent and that said Letters Patent are hereby corrected as shown below:

In the claims, Column 17, Claim 15 line 40 following 1 "Claim" delete"45" and I insert --7--.

Signed and sealed this 17th day of December 1974.

(SEAL) Attest:

McCOY M'. GIBSON JR.- c. MARSHALL DANN Attesting Officer Commissioner ofPatents FORM i USCOMM-DC 60376-P69 I "is. GOVERNMENT PRINTNG OFFICE; o

Disclaimer 3,739,69L-W6Zf7ed 8. Bobz'er- Bloomfield Hills, Mich. FLUIDDEVICE.

Patent dated June 19, 1973. Disclaimer filed Nov. 20, 1980, by theinventor.

Hereby enters this disclaimer to claim 7 of said patent.

[Oyficial Gazette February 10, 1.981.]

1. A fluid pressure energy translating device of the axial piston typecomprising: a housing; a cylinder barrel rotatably mounted about itslongitudinal axis within said housing, said cylinder barrel having aplurality of arcuately spaced cylinder bores communicating with bothlongitudinal ends of said cylinder barrel; a valve face having arcuatepassages, said valve face and one end of said cylinder barrel beingdisposed for relative rotary movement, with said cylinder barrel borescommunicating successively with said arcuate passages as said cylinderbarrel rotates; a plurality of pistons with inner ends disposed forreciprocal movement within said cylinder bores at the other end of saidcylinder barrel; a support member carried within said housing, saidsupport member having a pair of transversely spaced arcuately shapedbearing surfaces facing toward said other end of said cylinder barrel; amovable yoke constructed of a sintered metal material and having apiston engaging bearing surface on the side thereof facing the otherends of said pistons and cooperating therewith for imparting saidreciprocal movement to said pistons within said cylinder barrel bores assaid cylinder barrel rotates relative to said valve face, said movableyoke having laterally extending integral support pins with arcuatelyshaped bearing surfaces pivotably supported in said support memberarcuately shaped bearing surfaces, each of said yoke support pins havinga radial thickness as measured from said piston engaging bearing surfaceto the periphery of the support pin arcuate bearing surface which isapproximately 40 percent of the longitudinal thickness of said movableyoke as measured from said piston engaging bearing surface; means forvarying the inclination of said piston engaging bearing surface, saidlast mentioned means cooperating with said movable yoke to pivot saidmovable yoke about an axis defined by said arcuately shaped bearingsurfaces of said support pins, said means for varying the inclination ofsaid piston engaging bearing surface comprising an arm member carried byand radially extending from one of said support pins and pivotabletherewith about the axes of sAid support pins, and a displacementvarying mechanism carried externally of said housing and operativelycoupled to said arm member to pivot said arm and said movable memberabout the longitudinal axes of said support pins, said displacingvarying mechanism comprising a second housing carried by said firsthousing, said second housing having a longitudinal bore with a sleevemember adapted to be selectively reciprocated therein, said sleevemember having an internal threaded surface, a threaded member rotatablymounted about an axis concentric with the longitudinal axis of saidsecond housing bore and restrained against movement along said lastmentioned longitudinal axis, said threaded member having a threadedportion engaging said sleeve threaded surface such that rotation of saidthreaded member in opposite directions causes relative reciprocalmovement between said sleeve member and said second housing bore, saidsleeve member being operatively coupled through an aperture in saidhousing arm member to pivot said arm member and said movable yoke aboutthe axes of said support pins.
 2. A fluid pressure energy translatingdevice of the axial piston type comprising: a housing having alongitudinal bore; a cylinder barrel rotatably mounted about itslongitudinal axis within said housing bore, said cylinder barrel havinga plurality of arcuately spaced cylinder bores communicating with bothlongitudinal ends of said cylinder barrel; a valve face having arcuatepassages, said valve face and one end of said cylinder barrel beingdisposed for relative rotary movement, with said cylinder barrel borescommunicating successively with said arcuate passages as said cylinderbarrel rotates; a plurality of pistons with inner ends disposed forreciprocal movement within said cylinder bores at the other end of saidcylinder barrel; thrust plate means having a piston engaging bearingsurface on the side thereof facing the other ends of said pistons andcooperating therewith for imparting said reciprocal movement to saidpistons within said cylinder barrel bores as said cylinder barrelrotates relative to said valve face, said piston engaging bearingsurface being constructed of a sintered metal; a shaft rotatably mountedin said housing along the longitudinal axis of said bore, said cylinderbarrel being drivingly connected to and rotatable with said shaft;bearing means carried at one end of said housing bore, said bearingmeans mounting said shaft for rotational movement, said thrust platemeans being mounted in said housing bore and having a portion thereof inabutment with said last-mentioned bearing means to provide both properradial alignment of said thrust plate means with said shaft and properalignment of said thrust plate means with said cylinder barrel when saidthrust plate means is mounted on said bearing means, and wherein saidone end of said cylinder barrel has a plurality of elevated arcuatelyspaced bearing pads, said bearing pads being radially outwardly spacedfrom said cylinder ports, the inner cylinder port facing wall of each ofsaid bearing pads having a concave contour.
 3. A fluid pressure energytranslating device of the axial piston type comprising: a housing havinga longitudinal bore; a cylinder barrel rotatably mounted about itslongitudinal axis within said housing bore, said cylinder barrel havinga plurality of arcuately spaced cylinder bores communicating with bothlongitudinal ends of said cylinder barrel; a valve face having arcuatepassages, said valve face and one end of said cylinder barrel beingdisposed for relative rotary movement, with said cylinder barrel borescommunicating successively with said arcuate passages as said cylinderbarrel rotates; a plurality of pistons with inner ends disposed forreciprocal movement within said cylinder bores at the other end of saidcylinder barrel; thrust plate means having a piston engaging bearingsurface on the side thereof facing the other eNds of said pistons andcooperating therewith for imparting said reciprocal movement to saidpistons within said cylinder barrel bores as said cylinder barrelrotates relative to said valve face, said piston engaging bearingsurface being constructed of a sintered metal; a shaft rotatably mountedin said housing along the longitudinal axis of said bore, said cylinderbarrel being drivingly connected to and rotatable with said shaft;bearing means carried at one end of said housing bore, said bearingmeans mounting said shaft for rotational movement, said thrust platemeans being mounted in said housing bore and having a portion thereof inabutment with said last-mentioned bearing means to provide both properradial alignment of said thrust plate means with said shaft and properalignment of said thrust plate means with said cylinder barrel when saidthrust plate means is mounted on said bearing means, said thrust platemeans comprises a support member carried in said housing bore and havinga portion thereof in abutment with said bearing means to provide aproper radial alignment of said support member with said shaft, saidsupport member having a pair of transversely spaced arcuately shapedbearing surfaces facing toward said other end of said cylinder barrel; amovable yoke constructed of a sintered metal material and having saidpiston engaging bearing surface formed on the said thereof facing saidother ends of said pistons, said movable yoke having laterally extendingintegral support pins with arcuately shaped bearing surfaces pivotablysupported in said support member arcuately shaped bearing surfaces;means for varying the inclination of said piston engaging surface;bearing means having an outer race carried by said housing concentricwith said housing bore, said outer race having a portion of one sidesupported by each said support member; an inner race carried around aportion of the peripheral surface of said cylinder barrel; a pluralityof roller bearings disposed between said inner and outer races; and saidmeans for varying the inclination of said movable yoke comprising a pairof spaced sleeve members each disposed along axes paralleling the axisof said shaft and radially spaced from the peripheral surface of saidcylinder barrel, each of said sleeve members having one end of a pistonmember reciprocably mounted therein, the other ends of said pistonmembers adapted to abut a portion of said movable yoke to pivot saidmovable yoke about the longitudinal axes of said support pins, saidsleeves being radially spaced a distance from the centerline of saidshaft axis to abut the outer race of said bearing means to maintain saidouter race in a supporting abutment with said support member, saidpiston members being carried within said sleeves and so spaced from saidlongitudinal axis of said shaft as to freely reciprocate in a spacedrelationship with respect to the outer periphery of said outer race. 4.The fluid pressure energy translating device defined in claim 3 whereinthe yoke facing ends of said roller bearings and said inner race aresubstantially flush; a portion of said inner race extending beyond saidother end of said cylinder barrel and having an annular inclined innersurface flared upwardly from said other cylinder barrel end and towardsaid yoke facing end of said inner race.
 5. A fluid pressure energytranslating device of the axial piston type comprising: a housingconstructed of a plastic material; a cylinder barrel rotatably mountedabout its longitudinal axis within said plastic housing, said cylinderbarrel having a plurality of arcuately spaced cylinder borescommunicating with both longitudinal ends of said cylinder barrel; avalve face having arcuate passages, said valve face and one end of saidcylinder barrel being disposed for relative rotary movement, with saidcylinder barrel bores communicating successively with said arcuatepassages as said cylinder barrel rotates; a pluRality of pistons withinner ends disposed for reciprocal movement within said cylinder boresat the other end of said cylinder barrel; a support member carriedwithin said housing, said support member having a pair of transverselyspaced arcuately shaped bearing surfaces facing toward said other end ofsaid cylinder barrel; a movable yoke constructed of a sintered metalmaterial and having a piston engaging bearing surface on the sidethereof facing the other ends of said pistons and cooperating therewithfor imparting said reciprocal movement to said pistons within saidcylinder barrel bores as said cylinder barrel rotates relative to saidvalve face, said movable yoke having laterally extending integralsupport pins with arcuately shaped bearing surfaces pivotably supportedin said support member arcuately shaped bearing surfaces, each of saidyoke support pins having a radial thickness as measured from said pistonengaging bearing surface to the periphery of the support pin arcuatebearing surface which is approximately 40 percent of the longitudinalthickness of said movable yoke as measured from said piston engagingbearing surface; means for varying the inclination of said pistonengaging bearing surface, said last mentioned means cooperating withsaid movable yoke to pivot said movable yoke about an axis defined bysaid arcuately shaped bearing surfaces of said support pins, said meansfor varying the inclination of said piston engaging bearing surfacecomprising an arm member carried by and radially extending from one ofsaid support pins, and a displacement varying mechanism carriedexternally of said plastic housing and operatively coupled to said armmember to pivot said arm member about the axes of said support pins,said displacement varying mechanism comprising a second housing carriedby said plastic housing, said second housing having a longitudinal borewith a sleeve member adapted to be reciprocated therein, said sleevemember having an internal threaded surface, a threaded member rotatablymounted in a fixed position in said housing and adapted to rotate abouta longitudinal axis of said second housing bore, said threaded memberhaving a portion thereof engaging said sleeve member such that rotationof said threaded member in opposite directions produces reciprocalmoving between such sleeve member and said second housing bore, saidsleeve member being operatively coupled through an aperture in saidplastic housing to said arm member to pivot said arm member and saidmovable yoke about the axes of said support pins.
 6. A fluid pressureenergy translating device the axial piston type comprising: a housing; acylinder barrel rotatably mounted about its longitudinal axis withinsaid housing, said cylinder barrel having a plurality of arcuatelyspaced cylinder bores communicating with both longitudinal ends of saidcylinder barrel; a valve face having arcuate passages, said valve faceand one end of said cylinder barrel being disposed for relative rotarymovement, with said cylinder barrel bores communicating successivelywith said arcuate passages as said cylinder barrel rotates; a pluralityof pistons with inner ends disposed for reciprocal movement within saidcylinder bores at the other end of said cylinder barrel; a supportmember carried within said housing, said support member having a pair oftransversely spaced arcuately shaped bearing surfaces facing toward saidother end of said cylinder barrel; a movable yoke constructed of asintered metal material and having a piston engaging bearing surface onthe side thereof facing the other ends of said pistons and cooperatingtherewith for imparting said reciprocal movement to said pistons withinsaid cylinder barrel bores as said cylinder barrel rotates relative tosaid valve face, said movable yoke having laterally extending integralsupport pins with arcuately shaped bearing surfaces pivotably supportedin said support member arcuately shaped bearing surfaceS, each of saidyoke support pins having a radial thickness as measured from said pistonengaging bearing surface to the periphery of the support pin arcuatebearing surface which is approximately 40 percent of the longitudinalthickness of said movable yoke as measured from said piston engagingbearing surface; means for varying the inclination of said pistonengaging bearing surface, said last mentioned means cooperating withsaid movable yoke to pivot said movable yoke about an axis defined bysaid arcuately shaped bearing surfaces of said support pins, saidhousing having a longitudinal bore; a shaft rotatably mounted in saidhousing along the longitudinal axis of said bore, said cylinder barrelbeing drivingly connected to and rotatable with said shaft, and bearingmeans carried at one end of said housing mounting said shaft forrotational movement, said support member being mounted in said housingbore and having a portion thereof in abutment with said last mentionedbearing means to provide proper radial alignment of said support memberwith said shaft, said movable yoke being carried by said support membersuch that said movable yoke is properly aligned with said cylinderbarrel when said yoke support is mounted on said bearing means.
 7. Afluid pressure energy translating device of the axial piston typecomprising: a housing having a longitudinal bore; a cylinder barrelrotatably mounted about its longitudinal axis within said housing, saidcylinder barrel having a plurality of arcuately spaced cylinder borescommunicating with both longitudinal ends of said cylinder barrel; avalve face having arcuate passages, said valve face and one end of saidcylinder barrel being disposed for relative rotary movement, with saidcylinder barrel bores communicating successively with said arcuatepassages as said cylinder barrel rotates; a plurality of pistons withinner ends disposed for reciprocal movement within said cylinder boresat the other end of said cylinder barrel; a support member carriedwithin said housing, said support member having shaped bearing surfacesfacing toward said other end of said cylinder barrel; a movable yokehaving a piston engaging bearing surface on the side thereof facing theother ends of said pistons and cooperating therewith for imparting saidreciprocal movement to said pistons within said cylinder barrel bores assaid cylinder barrel rotates relative to said valve face, said movableyoke having complementary shaped bearing surfaces cooperating with saidsupport member shaped bearing surfaces; means for varying theinclination of said piston engaging bearing surface, said last-mentionedmeans cooperating with said movable yoke to pivot said movable yoke withrespect to said support member shaped bearing surfaces; a shaftrotatably mounted in said housing along the longitudinal axis of saidbore, said cylinder barrel being drivingly connected to and rotatablewith said shaft, and bearing means carried at one end of said housingmounting said shaft for rotational movement, said support member beingmounted in said housing bore and having a portion thereof in abutmentwith said last-mentioned bearing means to provide proper radialalignment of said support member with said shaft, said movable yokebeing carried by said support member such that said movable yoke isproperly aligned with said cylinder barrel when said yoke support ismounted on said bearing means.
 8. The fluid pressure energy translatingdevice defined in claim 7 wherein said housing is constructed of aplastic material.
 9. The fluid pressure energy translating devicedefined in claim 8 wherein said plastic housing is longitudinallyprecompressed a predetermined amount which is a function of the forcegenerated by the pressure of the fluid acting against the inner ends ofsaid pistons, said force tending to longitudinally expand said plastichousing.
 10. The fluid pressure energy translating device defined inclaim 7 whereiN said shaped bearing surfaces on said support member areconstructed of a plastic material.
 11. The fluid pressure energytranslating device defined in claim 7, further comprising: a bearingmeans having an outer race carried by said housing concentrically withsaid housing bore, an inner race carried around the peripheral surfaceof said cylinder barrel, and a plurality of roller bearings disposedbetween said inner and outer races, the yoke facing end of each of saidroller bearings and said inner race being substantially flush, a portionof said inner race extending beyond the other end of said cylinderbarrel and having an annular inclined inner surface flared upwardly fromsaid other cylinder barrel end toward said yoke facing end of said innerrace.
 12. The fluid device defined in claim 7 wherein said supportmember is constructed from a sintered metal material.
 13. The devicedefined in claim 7 further comprising an arcuately shaped member carriedby said support member and defining said support member shaped bearingsurface, said arcuately shaped bearing surfaces of said movable yokesupport pins being received and supported by said bearing members, saidbearing members being fabricated from a plastic material.
 14. The devicedefined in claim 7 further comprising bearing means having an outer racecarried within said housing; an inner race carried around a portion ofthe peripheral surface of said cylinder barrel; and a plurality ofroller bearings disposed between said inner and outer races, saidbearing means providing radial support for said cylinder barrel as saidcylinder barrel rotates, said bearing means being properly axiallypositioned within said housing by the abutment of one side of one ofsaid bearing races with a portion of said support member.
 15. The fluidpressure energy translating device defined in claim 45, wherein saidsupport member has a pair of transversely spaced arcuately shapedbearing surfaces facing toward said other end of said cylinder barrel; asaid movable yoke having said piston engaging bearing surface formed onthe side thereof facing said other ends of said pistons, said movableyoke having laterally extending integral support pins with saidcomplementary shaped bearing surfaces being pivotably supported in saidsupport member arcuately shaped bearing surfaces; and means for varyingthe inclination of said piston engaging surface.
 16. The fluid pressureenergy translating device defined in claim 15, wherein said means forvarying the inclination of said piston engaging surface cooperates withsaid movable yoke to pivot said movable yoke about an axis defined bysaid arcuately shaped bearing surfaces of said support pins.
 17. Thefluid pressure energy translating device in claim 15 wherein said meansfor varying the inclination of said movable yoke comprises: an armmember carried at the end of one of said support pins and pivotabletherewith about the axes of said support pins, and a displacementvarying mechanism carried externally of said housing and operativelycoupled to said arm member to pivot said arm member and said movableyoke about the axes of said support pins.
 18. The fluid pressure energytranslating device defined in claim 17 wherein said displacement varyingmechanism comprises: a second housing carried by said first housing andhaving a bore disposed along an axis extending transversely of saidlongitudinal axis, a manually operated shaft rotatably mounted in saidsecond housing bore, a second arm member radially extending from saidmanually operated shaft and operatively coupled through an aperture insaid device housing to said first mentioned arm member to pivot saidfirst mentioned arm and said movable yoke about the axes of said supportpins as said manually operated shaft is rotated in said second housingbore.
 19. The fluid pressure energy translating device defined in claim17 wherein said displacement varying mechanism carried comprises: asecond housing attached to said housinG, said second housing having abore with a pressure responsive member slidably mounted therein andbiased to a predetermined position, valve means responsive to apredetermined operating pressure of said fluid device to supply a secondpressure of predetermined value to said pressure responsive member tomove said pressure responsive member from said predetermined position,said pressure responsive member being operatively coupled to said armmember through an aperture in said device housing to pivot said armmember and said movable yoke about the axes of said support pins as saidpressure responsive piston moves from said predetermined position. 20.The fluid pressure energy translating device defined in claim 15,wherein said housing is constructed of a plastic material.
 21. The fluidpressure energy translating device defined in claim 20 wherein saidmeans for varying the inclination of said movable yoke comprises: an armmember carried by and radially extending from one of said support pinsand pivotable therewith about the axes of said support pins, and adisplacement varying mechanism carried externally of said housing andoperably coupled to said arm member to pivot said arm member about saidaxes of said support pins, said displacement varying mechanismcomprising: a second housing having a bore disposed along on axisextending transversely of said shaft axis; a manually operated shaftrotatably mounted in said second housing bore, a second arm memberradially extending from said second manually operated shaft andoperatively coupled through an aperture in said plastic housing to saidfirst mentioned arm member to pivot said first mentioned arm and saidmovable yoke about the axes of said support pins as said manuallyoperated shaft is rotated in said second housing bore.
 22. The fluidpressure energy translating device defined in claim 20 wherein saidmeans for varying the inclination of said thrust plate movable yokecomprises: an arm member carried by and radially extending from one ofsaid support pins and pivotable therewith along the axes of said supportpins; and a displacement varying mechanism carried externally of saidplastic housing and operatively coupled to through an aperture in saidplastic housing said arm member to pivot said arm member about thelongitudinal axes of said support pins, said displacement varyingmechanism comprising: the second housing attached to said plastichousing and having a bore with the pressure responsive member slidablymounted therein and biased to a predetermined position; valve meansresponsive to a predetermined operating pressure of said fluid device tosupply a second pressure of a predetermined value to said pressureresponse member to move said pressure responsive member from saidpredetermined position, said pressure responsive member beingoperatively coupled to said arm member to pivot said arm member and saidmovable yoke about the axes of said support pins as said pressureresponsive member moves from said predetermined position.
 23. The fluidpressure energy translating device defined in claim 20 wherein saidplastic housing is longitudinally precompressed a predetermined amountwhich is a function of the longitudinal expansion forces exerted on saidplastic housing by the pressure of the fluid acting against the innerends of said pistons within said cylinder barrel bores.